Researchers at UCLA say that there is an inverse relationship between the amount of caffeinated coffee a person drinks and his or her risk of developing type 2 diabetes. (The more coffee the less risk.) They say they think this is because caffeinated coffee increases the level of a protein called SHBG in the blood. SHBG regulates the biological activity of the sex hormones testosterone and estrogen and these have long been suspected of playing a role in the development of type 2 diabetes. Tests on women showed that those who drank 4 cups of caffeinated coffee a day had a 56% less chance of developing type 2 diabetes than those who drank none. Decaffeinated coffee does not increase SHBG and does not demonstrate the same protective effect.

Per the article:

"And there's bad news for decaf lovers. "Consumption of decaffeinated coffee was not significantly associated with SHBG levels, nor diabetes risk," Goto said. "So you probably have to go for the octane!""

The findings have been published in the current edition of the journal, Diabetes.